Plastic closure device for a tubular bag

ABSTRACT

The invention relates to a plastic closure device ( 1 ) for a tubular bag made of plastic or a multi-layer plastic film, comprising at least one bottom part ( 5 ) that has a spout ( 7 ), a spout opening ( 8 ), and a flange ( 4 ). The flange ( 4 ) has an energy-introduction arrangement ( 10 ) on the flange underside surface ( 9 ) of the flange. The energy-introduction arrangement can be connected to the plastic material or the plastic film of the tubular bag by means of ultrasonic welding. The energy-introduction arrangement ( 10 ) has at least one energy-introduction rib ( 12 ) arranged concentrically to the spout opening ( 8 ) in the peripheral region ( 11 ) of the flange ( 4 ). A concentrating rib ( 13 ) is provided on the flange underside surface ( 9 ). The concentrating rib extends within the energy-introduction arrangement ( 10 ) and protrudes from the flange underside surface ( 9 ) higher than the energy-introduction rib ( 12 ) and also extends directly adjacent to the spout opening ( 8 ).

BACKGROUND OF THE INVENTION

The present invention relates to a plastic closure device for a tubularbag.

SUMMARY OF THE INVENTION

The invention particularly relates to a plastic closure device for atubular bag from a plastic material or from a multilayered plastic film,in which the plastic closure device comprises at least one lower partwith a spout, a spout opening and a flange. A lower part of such a typeis provided for fastening onto a tubular bag by means of ultrasonicwelding; it therefore itself also consists of a thermoplastic. Moreover,in a lower part of such a type an energy-introducing arrangement isarranged on the flange on the face of the flange lower side, saidenergy-introducing arrangement serving to conduct and to concentrate theenergy introduced by means of ultrasound such that a welded connectionwhich is reliable and tight is created between the plastic parts(tubular bag and flange) to be connected. Usually, theenergy-introducing arrangement has to this end at least oneenergy-conducting rib which is arranged concentrically with the spoutopening in the peripheral region of the flange.

It is thus understood that the solution according to the inventionshould be suitable for what are referred to as tubular bags, usuallycalled “pouches” in industry language. Tubular bags of such a type arenowadays often manufactured from multilayered plastic films. Knownmultilayered plastic films have, for example, layered constructions asfollows: PP-AL-PE and PP-PETSiOx-PE. The ultrasonically weldable outerlayer thus often consists of polypropylene (PP) and the inner layer ofpolyethylene (PE). The intermediate layers often serve as protectionagainst light.

Moreover, it goes without saying that the plastic closure device as arule of course contains or may contain still further components, suchas, for example, an upper part in the form of a closure cap, an openingdevice and a tamper-proof band. Since these components, however, aremost likely known per se and not of consequence for the functionality ofthe invention, for the sake of simplification they have been eitherentirely omitted or, where necessary, only indicated.

Known solutions for plastic closure devices which are fastenable bymeans of ultrasonic welding are shown, for example, in documentJP-2000016453, two energy-conducting ribs which run concentrically tothe flange rim being shown here, or document JP-2000344264, which showsan identical plastic closure device for tubular bags in which merely oneenergy-conducting rib which runs concentrically with the flange rim ispresent.

A problem, which has already been alluded to in JP-2000016453, consistsin that, in the case of ultrasonic weldings of this type, there isalways a certain risk that what are referred to as “pinholes” arecreated in the sealing film in the region of the spout opening. Pinholesare undesirable small leakages which compromise the tightness of thetubular bag, which can of course lead to serious hygiene problems andshelf-life problems in the case of packaging for foodstuffs inparticular. The exact cause of the creation of pinholes does not appearto have been fully clarified as yet, such that it is to be assumed thatthe previous attempts at a solution are at least partly still of arather empirical nature. Overall, JP-2000016453 does not appear tocontain any detailed disclosure as to whether the solution with merelytwo energy-conducting ribs which run concentrically with the flange rimcan likewise reliably prevent a pinhole formation in the case of otheror merely similar designs too.

A further problem, which arises in particular in the case of plasticclosure devices having an opening device with a cutting device, consistsin that to improve or even to enable in the first place the ability tocut open in the region of the spout opening, a targeted weakening of thecontainer wall in the form of a scoring or another kind of formation ofa predetermined breaking point has to be provided locally. This is oftenthe case with film layers having a proportion of paper or cardboard, butit may often also be necessary in the case of film composites havingmultilayered plastic films. Of course, the configuration ofpredetermined breaking points depends on the type, the construction andthe thickness of the film composite. However, the introduction ofpredetermined breaking points in principle always has the disadvantagethat the plastic closure device has to be positioned very precisely inrelation to the tubular bag (or simply in relation to the container withwhich it is being used) during production, since as a rule even slightdeviations from the concentricity of the spout opening and thepredetermined breaking point lead to the cutting-out operation to someextent being greatly impeded or even made impossible. This is, ofcourse, particularly unpleasant when using beverage packagings, becausesplashes can, of course, very easily be created in the case of anincrease in the expenditure of force for opening, in particular in thecase of “soft” packaging of the tubular-bag type.

It is, therefore, the object of the invention to provide an improvedplastic closure device for tubular bags from plastic or a multilayeredplastic film.

The solution lies in that, in the case of a plastic closure device ofthe generic type for a tubular bag from plastic or from a multilayeredplastic film, which is connectable by means of ultrasonic welding to thetubular bag and which, for introducing the ultrasonic energy, has anenergy-introducing arrangement with energy-conducting ribs on a face ofthe flange lower side, a concentration rib, which runs centricallyoffset to the energy-conducting arrangement and which, with respect tothe energy-conducting rib, protrudes higher from the face of the flangelower side and is also arranged immediately adjacent to the spoutopening, is provided on the face of the flange lower side.

It has been demonstrated that the introduction of a concentration ribwhich runs within the energy-conducting arrangement and which, withrespect to the energy-conducting rib, protrudes higher from the face ofthe flange lower part and is also arranged immediately adjacent to thespout opening is even capable of combining a number of advantages.

On the one hand, this succeeds in collecting and redirecting theultrasonic energy to another site of action without undesirable sideeffects and in focusing it there, which ultrasonic energy, in the caseof annular sonotrodes used for ultrasonic welding, is otherwise mainlyconcentrated in the center of the sonotrodes and in this manner createsthe undesirable pinholes. It has been demonstrated, in fact, that thecreation of pinholes can be prevented with great reliability in this wayand that the suitability for storage particularly of packagings forfoodstuffs is thus greatly improved, since the tightness of thepackaging is ensured.

On the other hand, the ultrasonic energy redirected and focused in thisway can still also be utilized in a profitable way. Since the desiredsite of action of the redirected ultrasonic energy is now situated inthe immediate vicinity of the concentration rib, the resulting heatconcentration in this region causes a modification of the structure andthe shape in the plastic or in the multilayered plastic film of thetubular bag. Since, with respect to the energy-conducting rib or withrespect to the energy-conducting ribs, respectively, the concentrationrib protrudes higher from the face of the flange lower side, greaterheating results at this point upon the introduction of ultrasonicenergy. On account of this, the material of the plastic or of theplastic film is locally more strongly softened up and flows away fromthe concentration rib. The material thickness of the plastic or of theplastic film is thus reduced at this point. At the same time, afterremoval of the sonotrode and after cooling, a structural modification,which manifests itself as locally increased brittleness or as reducedelasticity of the plastic film, also still results in the plastic. Thus,along with the introduction of a concentration rib according to theinvention, a desirable predetermined breaking point is also stillobtained at the same time. The main advantage is, of course, that theotherwise additionally necessary operational steps, which would add costand reduce quality, for the separate manufacture of a weakened zone inthe spout region and the outlay for the precise positioning of theplastic closure device with respect to this weakened zone are completelydispensed with, since all this can be taken care of in a singleoperational step, namely the welding by means of ultrasound of theplastic closure device.

The arrangement according to the invention is particularly advantageousin the case of a plastic closure device which has an opening device withat least one cutting tooth, as long as said at least one cutting toothis movable in the vicinity of the concentration rib in order to cut openthe plastic material or the multilayered plastic film there. Since theenergy-conducting rib is arranged immediately adjacent to the spoutopening of the spout and the cutting tooth or the cutting teeth alsomove in the vicinity thereof, the cutting forces become effective in aweakened material region which, of course, facilitates the opening ofthe plastic closure device.

The concentration rib itself is advantageously provided with a roundedelevation, since in this way, rather than surface contact, linearcontact with the plastic or the multilayered plastic film material ofthe tubular bag is created, this leading to a higher concentration ofthe ultrasonic energy and thus to locally higher heating.

It is furthermore advantageous in many cases if the concentration rib isconfigured in a merely partially encircling manner around the spoutopening. In this way, it is possible to prevent or at least hinder theeasily removable piece (due to the weakening region) from falling fromthe spout region into the interior of the container. In the case ofplastic closure devices having an opening device with one or morecutting teeth, the possibility of positioning the only partiallyconfigured concentration rib along the circumference of the spoutopening—and thus also of that material part which can be cut outeasily—may also still be utilized in such a manner that the partiallycut-out material piece after completion of the cutting-out operationcomes to lie behind the cutting teeth in such a way that the openingcreated does not automatically (partially) close again as a result ofthe restoring forces.

It should additionally be mentioned in principle that the plasticclosure device according to the invention is suitable in principle forvarious types of opening devices (installed in the plastic closuredevice). Despite only being shown in the following by way of a singleexemplary embodiment having one opening device with a cutting device,applications with opening devices in which the plastic or themultilayered plastic film is pierced, punctured or torn off are alsopossible.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is now described in more detail by meansof an exemplary embodiment, in which

FIG. 1 shows the arrangement in principle of a plastic closure deviceand of a sonotrode in an ultrasonic welding operation,

FIG. 2 shows a partial side view of the lower part of a plastic closuredevice according to the invention, having an opening device,

FIG. 3 shows a partial sectional view of the lower part of the plasticclosure device as per FIG. 2, and

FIG. 4 shows the lower part in a simplified view from below.

DETAILED DESCRIPTION

FIG. 1 shows the arrangement in principle of a plastic closure device 1and of a sonotrode 2 for ultrasonic welding in an ultrasonic weldingoperation. To this end, the plastic closure device 1 is placed at thedesired point onto the shell material 3 (plastic or multilayered plasticfilm) of the tubular bag and then welded to the shell material 3 in theregion of a flange 4. It was already mentioned at the outset that theultrasonic energy in the case of annular sonotrodes used for ultrasonicwelding is at times preponderantly concentrated in a center region Zwhich is indicated by arrows and thus leads to the undesirable pinholesin this region of the shell material 3.

FIG. 2 shows a partial side view of a lower part 5 of a plastic closuredevice 1 according to the invention, having an opening device with acutting device 6 (see FIG. 3 in this context). The plastic closuredevice 1 comprises here at least the lower part 5 having a spout 7, aspout opening 8 and the flange 4. The spout opening 8 is, of course, athrough opening.

An energy-introducing arrangement 10, which is connectable by means ofultrasonic welding to the plastic material or the plastic film of thetubular bag, i.e. the shell material 3 of the tubular bag, is arrangedon the flange 4 on its face of the flange lower side 9.

The energy-introducing arrangement 10 is arranged concentrically withthe spout opening 8 in a peripheral region 11 of the flange 4 and has atleast one energy-conducting rib 12.

On the face of the flange lower side 9 a concentration rib 13 ispresent, which concentration rib 13 runs centrically offset to theenergy-conducting arrangement 10 and, with respect to theenergy-conducting rib 12, protrudes higher from the face of the flangelower side 9, and moreover is arranged immediately adjacent to the spoutopening 8. The concentration rib 13 is thus surrounded by theenergy-conducting arrangement 10.

Furthermore, the lower part 5 has an external thread 14 onto which aclosure-cap part (not illustrated), which likewise belongs to theplastic closure device, is screwed. Also visible are a retaining bead 15and a retaining cam 16 which, upon initial use, serve to sever atamper-proof band (likewise not illustrated) which belongs to theclosure-cap part from the latter. It is thus implied that the plasticclosure device 1 having an opening device with a cutting device shownhere is in principle of a known type in which, upon twisting off theclosure-cap part, both the tamper-proof band is torn off and also thecutting device 6 located in the interior of the lower part 5 is set intomotion in order to cut open the shell material 3 of the tubular bag inthe region of the spout opening 8.

FIG. 3 additionally shows a partial sectional view of the lower part 5of the plastic closure device 1 as per FIG. 2. Some details, inparticular the arrangement and the dimensional proportions of theenergy-introducing arrangement 10 having the energy-conducting rib 12and the concentration rib 13, can be more clearly identified here. Here,it is elucidated that the concentration rib 13 is a rounded elevation,or at least has a rounding. For a better understanding, the modificationregion 17, in which the material modification of the plastic towardhigher brittleness caused by the higher temperature in the vicinity ofthe concentration rib 13 takes place, is also indicated here.Furthermore, a severance line 18 is plotted, which severance line 18 isintended to elucidate in which region the at least one cutting tooth 19of the cutting device 6 (see FIG. 4 in this context) cuts through theshell material 3 upon opening of the plastic closure device. Theseverance line 18 is thus situated in the vicinity of the concentrationrib 13 and consequently at least also partially in the modificationregion 17.

Furthermore, part of an internal thread 20 which meshes with the cuttingdevice 6, merely schematically plotted in FIG. 4, is identifiable inFIG. 3. Upon opening of the plastic closure device, the cutting device 6is axiomatically rotated by means of the internal thread 20 and movedtoward the shell material 3.

Finally, FIG. 4 additionally shows the lower part 5 in a simplified viewfrom below, that is from direction A. It is clearly identifiable herethat the concentration rib 13 is arranged immediately adjacent to thespout opening 8 and that the concentration rib 13 here is configured ina merely partially encircling manner, namely approximately threequarters of the circumference, around the spout opening 8. The latteris, of course, a constructive detail and could also be selected so as tobe different. It appears to be important, however, that theconcentration rib 13 extends at least over the larger part of thecircumference in order that the concentration effect of the ultrasonicenergy aspired to also takes place to a sufficient degree, such that theeffect of the creation of pinholes in fact no longer arises.

The cutting device 6 is illustrated in FIG. 4 in a merely schematicmanner and above all with respect to its arrangement within the spoutopening 8. In the specific case, said cutting device 6 has a pluralityof relatively small cutting teeth 19 which are arranged at the end of anindicated hollow cylinder. This embodiment is, however, only exemplary,since many other forms of construction are possible.

1. A plastic closure device (1) for a tubular bag from plastic or from amultilayered plastic film, wherein the plastic closure device (1)comprises at least one lower part (5) with a spout (7), a spout opening(8) and a flange (4) having a flange lower side and a peripheral region,and wherein an energy-introducing arrangement (10), which is connectableby means of ultrasonic welding to the plastic material or to the plasticfilm of the tubular bag, is arranged on the flange (4) on a face of theflange lower side (9), and wherein the energy-introducing arrangement(10) has at least one energy-conducting rib (12) which is arrangedconcentrically with the spout opening (8) in the peripheral region (11)of the flange (4), characterized in that a concentration rib (13), whichruns centrically offset to the energy-introducing arrangement (10) and,with respect to the energy-conducting rib (12), protrudes higher fromthe face of the flange lower side (9) and is arranged immediatelyadjacent to the spout opening (8), is provided on the face of the flangelower side (9).
 2. The plastic closure device (1) as claimed in claim 1,characterized in that the concentration rib (13) is an elevation whichhas a rounded cross section.
 3. The plastic closure device (1) asclaimed in claim 1, characterized in that the concentration rib (13)extends in a circular manner along an entire inner circumference of theflange (4).
 4. The plastic closure device (1) as claimed in claim 1,characterized in that the concentration rib (13) extends along part ofan inner circumference of the flange (4).
 5. The plastic closure device(1) as claimed in claim 4, characterized in that the part of the innercircumference along which the concentration rib (13) extends is atmaximum 330°.
 6. The plastic closure device (1) as claimed in claim 1,characterized in that the plastic closure device (1) has an openingdevice with a cutting device (6) with at least one cutting tooth (19),wherein the at least one cutting tooth (19), during actuation of theplastic closure device (1), is movable in an encircling manner in avicinity of the concentration rib (13) in order to cut open the plasticmaterial or the multilayered plastic film.
 7. The plastic closure device(1) as claimed in claim 6, characterized in that the cutting device (6)is arranged and guided such that it cuts open only a pitch circle regionof the tubular bag, said pitch circle region running at least almostimmediately alongside the concentration rib (13).
 8. The plastic closuredevice (1) as claimed in claim 1, characterized in that furtherconducting ribs (21), which run radially to the at least oneenergy-conducting rib (12) substantially up to a periphery of the flange(4), are also provided.
 9. The plastic closure device (1) as claimed inclaim 4, characterized in that the part of the inner circumference alongwhich the concentration rib (13) extends 240° to 300°.
 10. The plasticclosure device (1) as claimed in claim 2, characterized in that theconcentration rib (13) extends in a circular manner along an entireinner circumference of the flange (4).
 11. The plastic closure device(1) as claimed in claim 2, characterized in that the concentration rib(13) extends along part of an inner circumference of the flange (4). 12.The plastic closure device (1) as claimed in claim 11, characterized inthat the part of the inner circumference along which the concentrationrib (13) extends is at maximum 330°.
 13. The plastic closure device (1)as claimed in claim 12, characterized in that the plastic closure device(1) has an opening device with a cutting device (6) with at least onecutting tooth (19), wherein the at least one cutting tooth (19), duringactuation of the plastic closure device (1), is movable in an encirclingmanner in a vicinity of the concentration rib (13) in order to cut openthe plastic material or the multilayered plastic film.
 14. The plasticclosure device (1) as claimed in claim 13, characterized in that thecutting device (6) is arranged and guided such that it cuts open only apitch circle region of the tubular bag, said pitch circle region runningat least almost immediately alongside the concentration rib (13). 15.The plastic closure device (1) as claimed in claim 14, characterized inthat further conducting ribs (21), which run radially to the at leastone energy-conducting rib (12) substantially up to a periphery of theflange (4), are also provided.
 16. The plastic closure device (1) asclaimed in claim 11, characterized in that the part of the innercircumference along which the concentration rib (13) extends 240° to300°.